The last time Nadal won 31 in a row in Paris, he failed to get No. 32, losing in the fourth round in 2009 to Robin Soderling. That remains the Spaniard's only defeat in 63 matches at the tournament.

He has dropped only 19 games this year, heading into a match against 83rd-ranked Dusan Lajovic of Serbia, who is in only the second Grand Slam tournament of his career and beat Jack Sock of the United States 6-4, 7-5, 6-3.

Before this French Open, the 23-year-old Lajovic had a 10-21 career record in tour-level matches, never winning two in a row.

The top-seeded Nadal made only 10 unforced errors against Mayer -- two in the first set, three in the second and five in the third. Still, there were moments when the match was far closer than the final score indicates, including when Mayer was serving at 5-all, deuce, in the second set.

After Mayer's forehand sailed long to set up a break point, Nadal converted it by stretching to scoop a backhand lob. As Mayer watched the shot sail overhead, he waved his left hand to signal to the ball to go out, then rolled his eyes when it curled in. At the other end, Nadal pumped his fist, ahead 6-5 in that set and well on his way to reaching the fourth round for the 10th time in trips to Roland Garros. Roger Federer, who won his third-round match Friday, is the only other man to make it to the final 16 in Paris that many years in a row.

The 83rd-ranked Lajovic saved 8 of 9 break points he faced against the 75th-ranked Sock, who was born in Nebraska and was trying to join John Isner as the first American men in the fourth round at Roland Garros since 2010.

Before this French Open, the 23-year-old Lajovic had a 10-21 career record in tour-level matches, never winning two in a row.

Sock, 21, has yet to reach the final 16 at a major.

Fellow American Donald Young was thwarted in his comeback attempt by Guillermo Garcia-Lopez, who beat Young 6-2, 6-4, 2-6, 6-7 (4), 6-4 to advance, making Isner the only American man in the fourth round.

The 41st-ranked Garcia-Lopez, who surprised No. 3 Stan Wawrinka in the first round, is in the final 16 at a major tournament for the first time.

Young, who is from Chicago, was trying to pull off his first victory in a match after dropping the first two sets, but Garcia-Lopez closed it out after more than 3½ hours.

Fifth-seeded David Ferrer, who lost to Nadal in last year's final, got to the fourth round by defeating No. 32 Andreas Seppi of Italy 6-2, 7-6 (2), 6-3.

Ferrer improved to 7-0 against Seppi, winning all 15 sets they've played. Ferrer, who has lost a total of 26 games through three matches this year in Paris, will face No. 19 Kevin Anderson of South Africa for a place in the quarterfinals.

Anderson advanced when Ivo Karlovic retired after one set Saturday because of a bad back.